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The formula to reduce your carbon footprint in wastewater treatment

The water treatment industry consumes significant amounts of energy. It is no wonder that ways to lower the carbon footprint are eagerly sought after. But wastewater itself could also be considered an energy source. Depending on the chosen treatment method, process energy-usage can be lowered and sustainable energy produced to benefit operations, society and the environment alike.

The formula to reduce your carbon footprint in wastewater treatment

Different water treatment technologies have different benefits. Biological treatment is good for the removal of dissolved organic substances and nitrogen. Chemical treatment is particularly efficient for phosphorus removal, preventing the eutrophication of our waterways, but also for the removal of particulate organic matter from the water. Best results and water treatment process stability are achieved by combining both treatment technologies.

Chemical pre-treatment reduces energy consumption

Chemical treatment of wastewater has been around for a long time. It’s safe, reliable and cost-effective. The same process that happens in nature. We just accelerate it in treatment plants.

“When you look at the carbon footprint of a water treatment facility, it is important to understand that the chosen process set-up and treatment method have a significant impact. Biological process consumes quite a bit of energy – in fact, about 50% of the total energy consumption of a wastewater plant. Several studies have been published to show this,” says Bengt Hansen, Senior Specialist in Application Development at Kemira. “Chemical treatment is very energy-efficient, especially when chemical pre-treatment is applied, before the biological step. The savings potential is up to 50% of the energy required in biological treatment.”

When you look at the carbon footprint of a water treatment facility, it is important to understand that the chosen process set-up and treatment method have a significant impact.

The share of biological treatment in the total energy consumption depends of course on plant design, location and treatment requirements. However, even if numbers vary, one conclusion is crystal clear from all studies: if less impurities are to be degraded biologically, less energy is required. This can be achieved by removing more impurities from water by chemical means, before the biological treatment.

“Chemical pre-treatment reduces energy consumption in the biological treatment and generates more biogas. By implementing chemical pre-treatment, the energy balance of a treatment plant can move from negative to positive values,” Bengt confirms.

Chemical pre-treatment produces more biogas

Wastewater contains energy in the form of organic matter. This is normally referred to as BOD, short for Bio-chemical/ Biological Oxygen Demand. The organic matter can either be transferred into carbon dioxide and biomass through an energy-consuming biological process or it can be converted into biogas through anaerobic digestion.

Biogas is sustainable energy that holds great potential. In most regions, this potential is yet to be fully utilized. There is a possibility to improve biogas production by selecting the right treatment process set-up. “Again, chemical pre-treatment produces the best results when it comes to biogas performance. By separating non-degraded organic matter in an early stage, the biogas potential increases. On top of that, the chemical used in the pre-treatment can support the biogas process itself to generate even more biogas,” Bengt concludes.

The carbon footprint of chemicals

Kemira’s focus is on offering products that help our customers do more with less – less raw materials, water and energy. We also pay close attention to the sustainability performance of our own production and offerings. Sustainability criteria is integrated into our new product development process. We have defined a Carbon Index to monitor our own CO2 performance from both consolidated and individual manufacturing site perspective. This is a long-term commitment and involves continuous development work. We have also calculated the carbon footprint of our key product lines. With our water treatment coagulant manufacturing, 70–80% of all raw materials used are recycled by-products from other industries, further reducing these products’ carbon footprint. In October 2019, we were rewarded with the chemical industry Responsible Care® award for such activity, and rank in the top quartile of the chemicals sector companies in the Carbon Disclosure Project (CDP) assesments.

To achieve maximum process efficiency, Kemira has developed a set of smart technologies for various applications like sludge dewatering, phosphorus removal, disinfection or primary treatment. Integrated algorithms enable automated process optimization, reinforcing the positive effects of chemical wastewater treatment.

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While acknowledging the invaluable role that biological processes play in wastewater treatment, chemical treatment brings some significant, measurable benefits when it comes to energy and plant optimization. Learn how to combine the best of both treatment techniques.

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